Electronically controlled electric system



y 4 19.54 K. J. GERMESHAUSEN ELECTRONICALLY CONTROLLED ELECTRIC SYSTEM Filed Aug. 30, 1947 QWU ll M w 0M M a W H .l MNQW ..w\

I77 21a 7720?" K6 7? new? if Germesimusew Patented May 4, 1954 UNITED STATES PATENT OFFICE ELECTRONICALLY CONTROLLED ELECTRIC SYSTEM The present invention relates to electric systerns, and more particularly to systems for producing intermittent or flashing light. Among the applications of the invention are strobo scopes, high-speed electrical flash photography and high-speed-motion-picture photography.

In each of Letters Patent of the United States 2,181,879, issued December 5, 1939, and 2,186,013, issued January 9, 1940, to Harold E. Edgerton, there is disclosed a gaseous-discharge lamp for producing a light flash upon the discharge therethrough of a condenser. The moment of discharge of the condenser is determined by a normally non-conducting low-impedance gas-filled grid-controlled tube or thyratron that, when rendered conducting, acts as a timing relay to set into operation apparatus for impressing a shorttime high-voltage large-current pulse, through a trigger transformer, upon a starting electrode of the gaseous-discharge lamp. The condenser thereupon sends a large current through the lamp, producing a flash.

For some purposes, it is often desirable to energize the starting electrode from a vacuum tube, instead of from the gas-filled grid-controlled tube before mentioned, and a system for the attainin of this end is disclosed in Letters Patent 2,426,602, issued September 2, 1947, to the said Harold E. Edgerton.

All object of the present invention is to provide a new and improved system of the above-described character comprising a vacuum tube for starting an electrical flash-lamp.

The use of vacuum tubes, operating on the principle of pure-electron discharge, as distinguished from gas-filled tubes, for controlling the energizing of the starting electrode has usually been. attended with practical difficulties. Among other factors, the conventional vacuum tubes ordinarily employed in amplifiers, oscillators and the like, owing to their relatively small cathodes and relatively large impedances, are not adapted for the passage of large current surges with the low tube drop necessary to energize a trigger transformer.

A further object of the present invention, therefore, is to provide a novel circuit in which conventional vacuum tubes may be employed to produce high-voltage surges of short duration.

Other and further objects Will be explained hereinafter and will be particularly pointed out in the appended claims.

The invention will now be described in connection with the accompanying drawings, in Which Fig. l is a diagrammati view of circuits and apparatus arranged and constructed according to one embodiment of the invention; and Fig. 2 is a similar fragmentary View of a modification.

A luminescent normally non-conductive electric flash-lamp is illustrated as of the gaseousdischarge, three-electrode type, provided with two principal internal electrodes in a glass envelope or tube 2, and a normally unenergized starting or control-grid electrode external thereto for rendering the lamp conductive between the cathode and the anode. The starting or control electrode 100 is shown as a wire twisted externally around the lamp. As disclosed in the said Letters Patent 2,426,602, lamps 2 having more electrodes may obviously also be employed. As also disclosed in the said Letters Patent 2,426,602, the lamp 2 may be straight, as illustrated, or it may be bent into U-shape, or twisted into spiral form, or it may have any other convenient shape. The gas contained in the tube may, for example, be mercury vapor, argon, neon, krypton or xenon, or the lamp may be filled with a mixture of any of these or other suitable gases.

The internal electrodes are illustrated as a solid metal cathode 4 and a solid metal anode 6. If desired, as is further disclosed in the said Letters Patent 2,426,602, one or both of these electrodes may be coated with other materials for facilitating starting the lamp, and the electrodes may, of course, assume other forms than those illustrated. The cathode 4 may, for example, as illustrated in each of the said Letters Patents 2,181,879 and 2,186,013, and as described also in the said Letters Patent 2,426,602, be constituted of a pool of mercury, and the startin electrode 106 may be in the form of an external metal band opposite to the meniscus of the mercury.

The cathode 4 and the anode 6 are shown connected in the output circuit of the tube 2, directly across a main discharge condenser 26. These connections may be made in any desired manner, as by means of wire conductors 8 and iii. The electrical flash-lamp 2 is flashed by the discharge of the condenser 26 therethrough, after it has become charged, through a current-limiting charging impedance 35, from any suitable source of direct-current energy, such as a battery 162. The impedance 35 is usually a combination of resistance and inductance. The quantity of light per flash from the lamp 2 is determined by the amount of energy in the condenser 26 and by circuit conditions.

To cause the flash-lamp 2 to start, the starting electrode I00 is shown connected to a secondary winding of a high-ratio step-up trigger flashing transformer 30. A voltage pulse accurately and reliably applied to the primary winding 35 of the transformer 30 from a source of direct-current voltage, will be transmitted to the secondary winding 29 to excite the starting electrode :00, thereby accurately and reliably starting the lamp 2.

A typical tube 2 may require a starting pulse of from 5,000 to 10,000 volts on the starting electrode 500. This pulse may be of very low amperage, the main requirement being that the voltage on the starting electrode I be suiiicient in magnitude to ionize the gas in the tube 2.

The timirn relay for controlling the production of the sudden large surges of current through the primary winding 35 of the flashing transformer 30 is shown in the form of a vacuum tube Hi0 that is normally non-conducting when not in oper ation, having at least three electrodes, namely, a main cathode electrode 48, a main plate or anode electrode 52 and a control grid electrode 50. A vacuum-tube triode M0 may be connected with the transformer 30 in such manner that, when it operates, the voltage of a battery I03 is momentarily applied across the primary winding 36, to produce a large current therein, whenever the tube 2 is to be set into operation. The starting instant may be controlled by controlling the potential between one of the main electrodes, namely, the cathode 08, and the control-grid electrode 50. The current between the anode and the cathode 48 may be controlled, and the electric discharge between them may be initiated, by varying the potential of the control-grid electrode 50 with respect to the cathode 40.

Since it is desirable to use small vacuum tubes I40 of the receiving type, the maximum voltage of the battery l0! may be limited to about 300 volts. The step-up-ratio between the windings 36 and 29 of the transformer 30 should therefore be high, on the order of 30 to 1. If the secondary winding has a large number of turns, its distributed capacity will be high. It will accordingly require considerable energy to charge this capacity; and to produce a high-voltage pulse of short duration across such a winding requires large current surges in the primary winding 30. If the number of turns of the secondary winding 29 should be reduced, the number of turns of the primary winding 30 should also be reduced, thus to maintain the ratio needed to step up the 300 volts applied to the primary winding 36 to the several thousand volts required to trigger the lamp 2. When the number of turns of the primary winding 30 is reduced, however, its impedance becomes row; and since the vacuum tube I40 is normally a high-impedance device, this would render it unable effectively to apply the voltage of the battery IilI across the primary winding 30 of the transformer 30.

It is because of considerations of this character that the tube I40 has heretofore been constituted of a low-impedance switching device, such as, the gas-filled tube or a thyratron, before mentioned. By careful design of the transformer 30, according to methods understood in. the art, it is possible to secure effective primary impedances of 500 to 1000 ohms.

It has not been practicable heretofore, as before stated, to substitute a small vacuum tube for the gas-filled thyratron I40, because such small vacuum tubes have nominal internal impedances of 5,000 to 10,000 ohms. When a small vacuum tube I40 of this character is rendered conducting, therefore, only a small fraction of the voltage of the battery IOI could appear across the primary winding The impedance of a small vacuum tube I40 can, however, be momentarily much reduced by driving its normally negatively biased grid 50 temporarily positive. By this expedient, it is. pos sible to obtain appreciable grid currents. A small triode MB of the receiving type, operated in this way, may have an internal impedance as low as 50 to ohms, while passing currents on the order of several amperes. Operated in this mannor, a small vacuum tube M0 may be practically employed as the switching means for applying pulses of voltage across the primary winding 36 of the trigger transformer 30.

One method of securing the necessary momentary positive grid drive on the tube I40, whereby its internal impedance is rendered low enough to energize the transformer 30, involves connecting this type of tube I40 into a blocking-oscillator circuit.

The secondary winding 20 of the transformer 30 is shown connected in the input circuit of the tube 2, between the cathode t and the external electrode 00. The primary winding 36 of thistransformer 30 is connected in the power-output or plate circuit of the vacuum tube M0, This power-output circuit may be traced from the cathode 40, through the tube I40, to the anode 52, and through the primary winding 36 and the battery 5 0 i, back to the cathode 48. This poweroutput circuit is normally open, because of a normally very strongly negative bias on the grid 50 with respect to the cathode i8, provided by a biasing battery I03, with or without a potentiometer 38, through resistors 33 and 40. This renders the vacuum tube Hi0 normally non-conducting, as before described. The power-output circuit becomes essentially short-circuited, however, whenever the grid 50 is subjected to a suitable stimulus, whereupon it serves as a discharge circuit for the battery IOI.

One input or grid circuit of the vacuum tube I40 may be traced from the cathode 18, through the control grid 50, the resistor 30, a condenser or capacitor 59, a further secondary winding 28 of the transformer 30, and the battery I01, back to the cathode d8.

A second. input circuit for the tube Hi0 ma be traced from the cathode 48, through the control grid the resistor a condenser 00, and terminals 32, back to the cathode &8.

To the tube M0 conducting, a positive trigger pulse may be applied across the terminals 32 in the second input circuit of the tube I40. The voltage of the control grid 50 becomes thereupon raised to a value above cut-off. Ehis renders the tube i i-0 slightly conducting, whereupon a voltage pulse from the battery IOI appears in the power-output circuit of the vacuum tube I40, across the primary winding 30 of the transformer The voltage pulse appearing across the primary winding will communicated to the secondary windings 28 and The winding 23, or approximately the same number of turns as the primary winding 30, is connected with such polarity that the pulse appearing across it shall tend to drive the grid 50 still more positive.

This process is rapidly repeated cumulatively until the positive voltage upon the grid 50 is increased sufficiently to r nder the vacuum tube I 40 sufficiently conductive, without further aid from the original trigger pulse, to produce a large voltage pulse across, and a large current in, the 'winding 36. The current thus produced through the vacuum tube I40, as before stated, may be on the order of several amperes. A sufficiently large sudden positive high-voltage triggering pulse becomes thus impressed accurately, reliably and rapidly upon the primary winding 36. Because of the relatively high impedance of the secondary winding 29, a high-voltage low-current pulse becomes thereupon communicated to the secondary winding 29 from the low-voltage source IOI. An energizing pulse therefore becomes impressed upon the starting electrode E59 of voltage sufllcient to enable the condenser 25 to discharge through the lamp 2, thereby to produce a momentary flash between the cathode i and the anode 6. This result is attained with only a single vacuum tube H0.

Since the grid 59 draws current during this operation, the condenser 59 will become charged, allowing the grid 59 to return to the large negative bias. ihus shutting oif the tube I40, it will remain in this condition until another positive pulse is applied to the terminals 32.

If the bias on the grid 50 is adjusted, as by means of a potentiometer 38, to a value somewhat less than cut-oif, as shown in Fig. 2, the circuit will go into self-oscillation at a frequency determined largely by the time constants of the condenser 59 and the resistor 33. The oscillator will render the starting electrode ma effective and ineffective periodically, during each cycle of its oscillations. This type of operation is useful when it is desired to operate the flash lamp 2 repetitively at regular intervals, as for stroboscopic purposes.

The invention is also effective for starting gas filled tubes for rectifiers or inverters, as well as for light-flash sources. In all cases, the vacuum tube I49 controls the operation of the starting electrode iii} to control the discharges of the condenser 26 through the discharge tube 2.

Further modifications will occur to persons skilled in the art, and all such are considered to fall within the spirit and scope of the invention, as defined in the appended calims.

What is claimed is:

1. An electric system having, in combination, a gaseous-discharge device, a transformer having a primary winding and two secondary windings one of which is connected to a source of energy, the said one secondary winding having a relatively high impedance, a vacuum tube connected to the primary winding operating on the principle of a pure electron discharge, means maintaining the vacuum tube normally non-conducting when not in operation, means comprising the other secondary winding for rendering the vacuum tube conducting, means controlled by the vacuum tube upon its becoming conducting to energize the primary winding, and means thereupon con trolled by the said one secondary winding for transferring energy from the source to the gaseous-discharge device to energize the gaseousdischarge device.

2. A flash-producing system having, in combination, a flash device, a transformer having a primary winding and a secondary winding connected to a source of energy, a vacuum tube connected to the primary winding operating on the principle of a pure-electron discharge, means maintaining the vacuum tube normally non-com ducting when not in operation, means rendering the vacuum tube conducting, means controlled by the vacuum tube upon its becoming conduct- 6 ing to energize the primary winding, and means thereupon controlled by the secondary winding for transferring energy from the source to the flash device to cause the flash device to produce a flash.

3. An electric system having, in combination, a gaseous-discharge device, means for energizing the gaseous-discharge device, a transformer having a primary winding and two secondary Windings one of which is connected to the energizing means, a vacuum tube connected to the primary winding operating on the principle of a pureelectron discharge and having a normally negatively biased control electrode for maintaining the vacuum tube normally non-conducting when not in operation to render the energizing means normally ineliective, means for impressing a slightly positive voltage pulse on the control electrode to render the vacuum tube slightly conducting, means controlled by the vacuum tube upon its becoming conducting to energize the primary winding, means controlled by the other secondary winding for thereupon increasing the positive voltage on the control electrode to increase the conduction of the vacuum tube suificiently to energize the said one secondary winding through the primary winding sufiiciently to render the energizing means effective, and means controlled by the said other secondary winding for thereupon restoring the normal negative bias of the control electrode.

4. A flash-producing system having, in combination, a flash device, means for energizing the flash device to cause the flash device to produce a flash, a transformer having a primary winding and two secondary windings one of which is connected to the energizing means, a vacuum tub connected to the primary winding operating on the principle of a pure-electron discharge and having a normally negatively biased control electrode for maintaining the vacuum tube normally non-conducting when not in operation to render the energizing means normally ineffective, means for impressing a slightly positive voltage pulse on the control electrode to render the vacuum tube slightly conducting, means controlled by the vacuum tube upon its becoming conducting to energize the primary winding, means controlled by the other secondary winding for thereupon increasing the positive voltage on the control electrode to increase the conduction of the vacuum tube sufficiently to energize the said one secondary winding through the primary winding sufficiently to render the energizing means effective, and means controlled by the said other secondary winding for thereupon restoring the normal negative bias of the control electrode.

5. A stroboscope having, in combination, a flash device, means for energizing the flash device to cause the flash device to produce a flash, a vacuum tube operating on the principle of pure-electron discharge and having a normally biased control electrode for maintaining the vacuum tube normally non-conducting when not in operation to render the energizing means normally ineffective, and means for periodically changing the bias of the control electrode slightly in order periodically to render the vacuum tube slightly conducting and for thereupon periodically increasing the change in the bias to increase periodically the conduction of the vacuum tube sufficiently to render the energizing means periodically efiective.

6. An electric system having, in combination, a gaseous-discharge device having a control electrode, a condenser, means for charging the condenser, a transformer having a primary winding and two secondary windings one of which is connected to the control electrode, a vacuum tube having a normally biased control electrode for maintaining the vacuum tube normally non-conducting when not in operation, means for connecting the primary winding to a source of energy in circuit with the vacuum tube in order to supply energy from the source to the primary winding when the vacuum tube is conducting, means connecting the other secondary winding to the vacuum-tube control electrode, and means for impressing a voltage pulse on the vacuumtube control electrode to render the vacuum tube sligthly conducting, whereupon a slight amount of energy will be supplied from the source to the primary winding in circuit with the vacuum tube to transmit a pulse through the primary winding to the said other secondary winding and through the said other secondary winding to the vacuum-tube control electrode further to change the voltage on the vacuum-tube control electrode, thereby to increase the conduction of the vacuum tube sufliciently to enable the source to supply a sufficient amount or" energy to the primary winding in circuit with the vacuum tube to enable the primary winding to impress a pulse through the said one secondary winding upon the gaseousdischarge-device control electrode in order that the condenser may discharge through the gaseous-discharge device.

'7. A flash-producing system having, in combination, a flash device having a control electrode, a condenser, means for charging the condenser, a transformer having a primary winding and two secondary windings one of which is connected to th control electrode, a vacuum tube having a normally biased control electrode for maintaining the vacuum tube normally nonconducting when not in operation, means for connecting the primary winding to a source of energy in circuit with the vacuum tube in order to supply energy from the source to the primary winding when the vacuum tube is conducting, means connecting the other secondary winding to the vacuum-tube control electrode, and means for impressing a voltage pulse on the vacuumtube control electrode to render the vacuum tube slightly conducting, whereupon a slight amount of energy will be supplied from the source to the primary Winding in circuit with the vacuum tube to transmit a pulse through the primary winding to the said other secondary winding and through the said other secondary winding to the vacuumtube control electrode further to change the voltage on the vacuum-tube control electrode, thereby to increase the conduction of the vacuum tube sufficiently to enable the source to supply a suflicient amount of energy to the primary winding in circuit with the vacuum tube to enable the primary winding to impress a pulse through the said one secondary winding upon the flashdevice control electrode in order that the condenser may discharge through the flash device to produce a flash.

8. An electric system having, in combination, a gaseous-discharge device having a control electrode, a condenser, means for charging the condenser, a transformer having a primary winding and two secondary windings one of which is connected to the control electrode, a vacuum tube having a normally negatively biased control electrode for maintaining the vacuum tube normally non-conducting when not in operation,

means for connecting the primary winding to a source of energy in circuit with the vacuum tube in order to supply energy from the source to the primary winding when the vacuum tube is conducting, means connecting the other secondary winding to the vacuum-tube control electrode, and means for impressing a slightly positive voltage pulse on the vacuum-tube control electrode to render the vacuum tube slightly conducting, whereupon a slight amount of energy will be supplied from the source to the primary winding in circuit with the vacuum tube to transmit a pulse through the primary winding to the said other secondary winding and through the said other secondary winding to the vacuumtube control electrode to increase the positive voltage on the vacuum-tube control electrode, thereby to increase the conduction of the vacuum tube sufficiently to enable the source to supply a sufiicient amount or" energy to the primary winding in circuit with the vacuum tube to enable the primary winding to impress a pulse through the said one secondary winding upon the gaseous-discharge-device control electrode in order that the condenser may discharge through the gaseous-discharge device.

9. A flash-producing system having, in combination, a flash device having a control electrode, a condenser, means for charging the condenser, a transformer having a primary winding and two secondary windings one of which is connected to the control electrode, a vacuum tube having a normally negatively biased control electrode for maintaining the vacuum tube normally nonconducting when not in operation, means for connecting the primary winding to a source of energy in circuit with the vacuum tube in order to supply energy from the source to the primary winding when the vacuum tube is conducting, means connecting the other secondary winding to the vacuum-tube control electrode, and means for impressing a slightly positive voltage pulse on the vacuum-tube control electrode to render the vacuum tube slightly conducting, whereupon a slight amount of energy will be supplied from the source to the primary winding in circuit with the vacuum tube to transmit a pulse through the primary winding to the said other secondary winding and through the said other secondary winding to the vacuum-tube control electrode to increase the positive voltage on the vacuum-tube control electrode, thereby to increase the conduction of the vacuum tube sumciently to enable the source to supply a sufficient amount of energy to the primary winding in circuit with the vacuum tube to enable the primary winding to impress a pulse through the said one secondary winding upon the flash-device control electrode in order that the condenser may discharge through the flash device to produce a flash.

10. An electric system having, in combination, a gaseous-discharge device, means for energizing the gaseous-discharge device, a trigger transformer having a primary winding and two secondary windings one of which is connected to the energizing means, the said one secondary winding having a relatively high impedance, a highimpedance vacuum tube connected to the primary winding and having a normally negatively biased control electrode for maintaining the vacuum tube normally non-conducting when not in operation to render the energizing means normally ineffective, means comprising the other secondary winding for impressing a positive voltage pulse on the control electrode to lower the impedance of the vacuum tube, thereby to render the vacuum tube sufliciently conducting to energize the primary winding, and means thereupon controlled by the said one secondary winding to render the energizing means effective.

11. A flash-producing system having, in combination, a flash device, means for energizing the flash device to cause the flash device to produce a flash, a trigger transformer having a primary winding and a secondary winding connected to the energizing means, a high-impedance vacuum tube connected to the primary winding and having a normally negatively biased control electrode for maintaining the vacuum tube norma ly non-conducting when not in operation to render the energizing means normally ineffective, means for impressing a positive voltage pulse on the control electrode to lower the impedance of the vacuum tube, thereby to render the vacuum tube sufliciently conducting to energize the primary winding, and means thereupon controlled by the secondary winding to render the energizing means eflfective.

12. A flash-producing system having, in combination, a flash device, a transformer having a primary winding and a secondary winding, a vacuum tube that is normally non-conducting when not in operation having an input circuit in which the secondary winding is connected and an output circuit in which the primary winding is connected, means for rendering the vacuum tube conducting, means operative through the cooperation of the primary and secondary windings for producing a voltage pulse in the output circuit from a source of energy upon the vacuum tube becoming conducting, and means for coupling the output circuit to the flash device to transmit the voltage pulse to the flash device in order to cause the flash device to produce a flash.

13. A flash-producing system having, in combination, a flash device, a transformer having a primary winding and a secondary winding, a vacuum tube that is normally non-conducting when not in operation having an input circuit in which the secondary winding is connected and an output circuit in which the primary winding is connected, means coupled to the output circuit for energizing the flash device in response to a voltage pulse of predetermined magnitude i order to cause the flash device to produce a flash, means operative when the vacuum tube has been rendered conductive to a predetermined degree to supply to the output circuit from a source of energy a voltage suflicient to impress a voltage pulse of the predetermined magnitude upon the energizing means, means for initially rendering the vacuum tube slightly conducting, thereby to initiate the supply of a slight amount of energy from the source to the output circuit, and means operative through the cooperation of the primary and secondary windings to cause the input circuit, upon the vacuum tube becoming slightly conducting, cumulatively to draw energy from the output circuit to render the vacuum tube cumulatively increasingly conducting in order cumulatively to increase the conduction of the vacuum tube to the predetermined degree.

14. An electric discharge producing system having, in combination, an electric-discharge device, a transformer having a primary winding and a secondary winding, a vacuum tube that is normally non-conducting when not in operation having an input circuit in which the secondary winding is connected ad a output circuit in which the primary winding is connected, means for rendering the vacuum tube conducting, means operative through the cooperation of the primary and secondary windings for producing a voltage pulse in the output circuit from a source of energy upon the vacuum tube becoming conducting, and means for coupling the output circuit to the electric-discharge device to transmit the voltage pulse to the electric-discharge device in order to cause the flash device to produce a discharge.

15. An electric-discharge producing system having, in combination an electric-discharge device, a transformer having a primary winding and a secondary winding, a vacuum tube that is normally non-conducting when not in operation having an input circuit in which the secondary winding is connected ad a output circuit in which the primary winding is connected, means coupled to the output circuit for energizing the electric-discharge device in response to a voltage pulse of predetermined magnitude in order to cause the electric-discharge device to produce a discharge, means operative when the vacuum tube has been rendered conductive to a predetermined degree to supply to the output circuit from a source of energy a voltage suflicient to impress a voltage pulse of the predetermined magnitude upon the energizing means, means for initially rendering the vacuum tube slightly conducting, thereby to initiate the supply of a slight amount of energy from the source to the output circuit, and means operative through the cooperation of the primary and secondary windings to cause the input circuit, upon the vacuum tube becoming slightly conducting, cumulatively to draw energy from the output circuit to render the vacuum tube cumulatively increasingly conducting in order cumulatively to increase the conduction of the vacuum tube to the predetermined degree.

16. A flash-producing system having, in combination, a flash device, a condenser, means for charging the condenser, a transformer having a primary winding and a secondary winding, a vacuum tube that is normally non-conducting when not in operation having an input circuit in which the secondary winding is connected and an output circuit in which the primary winding is connected, means for rendering the vacuum tube conducting, means operative through the cooperation of the primary and secondary windings for producing a voltage pulse in the output circuit from a source of energy upon the vacuum tube becoming conducting, and means for coupling the output circuit to the flash device to transmit the voltage pulse to the flash device in order to discharge the condenser through the flash device to cause the flash device to produce a flash.

17. A flash-producing system having, in com bination, a gaseous-discharge flash device, .a condenser, means for charging the condenser, a transformer having a primary winding and a secondary winding, a vacuum tube that is normally nonconducting when not in operation having an input circuit in which the secondary winding is connected and an output circuit in which the primary winding is connected, means coupled to the output circuit for energizing the flash device in response to a voltage pulse of predetermined magnitude in order to discharge the condenser through the flash device to cause the flash device to produce a flash, means operative when the vacuum. tube has been rendered luau conducting to a predetermined degree to supply to the output circuit from a source of energy a voltage sufficient to impress a voltage pulse of the predetermined magnitude upon the energizing means, means for initially rendering the vacuum tube slightly conducting, thereby to initiate the supply of a slight amount of energy from the source to the output circuit, and means operative through the cooperation of the primary and secondary windings to cause the input circuit, upon the vacuum tube becoming slightly conducting, cumulatively to draw energy from the output circuit to render the vacuum tube cumulatively increasingly conducting in order cumulatively to increase the conduction of the vacuum tube to the predetermined degree.

18. An electric-discharge producing system having, in combination, an electric-discharge device, a condenser, means for charging the condenser, a transformer having a primary winding and a secondary winding, a vacuum tube that is normally non-conducting when not in operation, having an input circuit in which the secondary winding is connected and an output circuit in which the primary winding is connected, means for rendering the vacuum tube conducting, means operative through the cooperation of the primary and secondary windings for producing a voltage pulse in the output circuit from a source of energy upon the vacuum tube becoming conducting, and means for coupling the output circuit to the electric-discharge device to transmit the voltage pulse to the electric-discharge device in order to discharge the condenser through the electricdischarge device.

19. A flash-producing system having, in combination, an electric-discharge flash device, a condenser, means for charging the condenser, a transformer having a primary winding and a secondary winding, an electron amplifier device that is normally non-conducting when not in operation having an input circuit in which the secondary winding is connected and an output circuit in which the primary winding is connected, means coupled to the output circuit for energizing the flash device in response to a voltage pulse of predetermined magnitude in order to discharge the condenser through the flash device to cause the flash device to produce an electric flash, means operative when the amplifier device has been rendered conducting to a predetermined degree to supply to the output circuit from a source of energy a voltage sufflcient to impress a voltage pulse of the predetermined magnitude upon the energizing means, means for initially rendering the amplifier device slightly conducting, thereby to initiate the supply of a slight amount of energy from the source to the output circuit, and means operative through the cooperation of the primary and secondary windings to cause the input circuit, upon the amplifier device becoming slightly conducting, cumulatively to draw energy from the output circuit to render the amplifier device cumulatively increasingly conducting in order cumulatively to increase the conduction oi? the amplifier device to the predetermined degree.

20. A flash-producing system having, in combination, an electric-discharge flash device, a transformer having a primary winding and a secondary winding, a vacuum tube having two main electrodes, a control electrode, an input circuit connected to one of the main electrodes and the control electrode in which the secondary winding is connected and an output circuit connected to the main electrodes in which the primary winding is connected, means for normally biasing the control electrode to maintain the vacuum tube normally non-conducting when not in operation, means coupled to the output circuit for energizing the flash device in response to a voltage pulse of predetermined magnitude in order to cause the flash device to produce an electric flash, means operative when the vacuum tube has been rendered conducting to a predetermined degree to supply to the output circuit from a source of energy a voltage sufiicient to impress a voltage pulse of the predetermined magnitude upon the energizing means, means for initially changing the bias of the control electrode slightly to render the vacuum tube slightly conducting, thereby to initiate the supply of a slight amount of energy from the source to the output circuit, and means operative through the cooperation of the primary and secondary windings to cause the input circuit, upon the vacuum tube becoming slightly conducting, cumulatively to increase the change in the bias of the control electrode in order cumulatively to draw energy from the output circuit to render the vacuum tube cumulatively increasingly conducting in order cumulatively to increase the conduction of the vacuum tube to the predetermined degree.

21. A flash-producing system having, in combination, a gaseous-discharge flash device, a transformer having a primary winding and a secondary winding, a vacuum tube having two main electrodes, a control electrode, an input circuit connected to one of the main electrodes and the control electrode in which the secondary winding is connected and an output circuit connected to the main electrodes in which the pri mary winding is connected, means for normally biasing the control electrodes negatively to maintain the vacuum tube normally non-conducting when not in operation, means coupled to the output circuit for energizing the flash device in response to a voltage pulse of predetermined magnitude in order to cause the flash device to produce a flash, means operative when the vacuum tube has been rendered conductive to a predetermined degree to supply to the output circuit from a source of energy a voltage sufiicient to impress a voltage pulse of the predetermined mag nitude upon the energizing means, means for initially impressing a slightly positive voltage pulse on the control electrode to render the vacuum tube slightly conducting, thereby to initiate the supply of a slight amount of energy from the source to the output circuit, and means operative through the cooperation of the primary and secondary windings to cause the input circuit, upon the vacuum tube becoming slightly conducting, cumulatively to increase the positive voltage on the control electrode in order cumulatively to draw energy from the output circuit to render the vacuum tube cumulatively increasingly conducting in order cumulatively to increase the conduction of the vacuum tube to the predetermined degree.

22. A flash-producing system having, in combination, a flash device, a transformer having a primary winding and a secondary winding, a vacuum tube having two main electrodes, a control electrode, an input circuit connected to one of the main electrodes and the control electrode in which the secondary winding is connected and an output circuit connected to the main electrodes in which the primary winding is connected, means for normally biasing the control electrode negatively to maintain the vacuum tube normally non-conducting when not in operation, means coupled to the output circuit for energizing the flash device in response to a voltage pulse of predetermined magnitude in order to cause the flash device to produce a flash, means operative when the vacuum tube has been rendered conducting to a predetermined degree to supply to the output circuit from a source of energy a voltage suflicient to impress a voltage pulse of the predetermined magnitude upon the energizing means, means for initially impressing a slightly positive voltage pulse on the control electrode to render the vacuum tube slightly conducting, thereby to initiate the supply of a slight amount of energy from the source to the output circuit, means operative through the cooperation of the primary and secondary windings to cause the input circuit, upon the vacuum tube becoming slightly conducting, cumulatively to increase the positive voltage on the control electrode in order cumulatively to draw energy from the output circuit to render the vacuum tube cumulatively increasingly conducting in order cumulatively to increase the conduction of the vacuum tube to the predetermined degree, and means controlled by the secondary winding for restoring the normal negative bias of the control electrode.

23. A flash-producing system having, in combination, a flash device, a transformer having a primary winding and a secondary winding, an electron amplifier device that is normally nonconducting when not in operation having three electrodes, an input circuit connected between two of the electrodes in which the secondary winding is connected and an output circuit connected between one of the said two electrodes and the third electrode in which the primary winding is connected, means coupled to the output circuit for energizing the flash device in response to a voltage pulse of predetermined magnitude in order to cause the flash device to produce a flash, means operative when the amplifier device has been rendered conducting to a predetermined degree to supply to the output circuit from a source of energy a voltage sufilcient to impress a voltage pulse of the predetermined magnitude upon the energizing means, means for initially applying a slightly positive voltage between the said two electrodes to render the amplifier device slightly conducting thereby to initiate the supply of a slight amount of energy from the source to the output circuit, and means operative through the cooperation of the primary and secondary windings to cause the input circuit, upon the amplifier device becoming slightly conducting, cumulatively to increase the positive voltage between the said two electrodes to draw energy from the output circuit to render the amplifier device cumulatively increasingly conducting in order cumulatively to increase the conduction of the amplifier device to the predetermined degree.

24; A flash-producing system having, in combination, a flash device, a first condenser, means for charging the first condenser, a transformer having a primary winding and a secondary winding, a second condenser, a vacuum tube having two main electrodes, a control electrode, an input circuit connected to one of the main electrodes and the control electrode in which the secondary winding and the second condenser are connected and an output circuit connected to the main electrodes in which the primary winding is connected, means for normally biasing the control electrode negatively to maintain the vacuum tube normally non-conducting when not in operation, means coupled to the output circuit for energizing the flash device in response to a voltage pulse of predetermined magnitude in order to discharge the first condenser through the flash device to cause the flash device to produce a flash, means operative when the vacuum tube has been rendered conductive to a predetermined degree tosupply to the output circuit from a source of energy a voltage sufiicient to impress a voltage pulse of the predetermined magnitude upon the energizing means, means for initiall impressing a slightly positive voltage pulse on the control electrode to render the vacuum tube slightly conducting, thereby to initiate the supply of a slight amount of energy from the source to the output circuit, and means operative through the cooperation of the primary and secondary windings to cause the input circuit, upon the vacuum tube becoming slightly conducting, cumulatively to increase the positive voltage on the control electrode in order cumulatively to draw energy from the output circuit to render the vacuum tube cumulatively increasingly conducting in order cumulatively to increase the conduction of the vacuum tube to the predetermined degree and cumulatively to charge the second condenser during the cumulative increase of the positive voltage on the control electrode in order to restore the normal negative bias of the control electrode.

25. A stroboscope having, in combination, a flash device, a transformer having a primary Winding and a secondary winding, a vacuum tube having two main electrodes, a control electrode, an input circuit connected to one of the main electrodes and the control electrode in which the secondary winding is connected and an output circuit connected to the main electrodes in which the primary winding is connected, means for normally biasing the control electrode to maintain the vacuum tube normally non-conducting when not in operation, means coupled to the output circuit for energizing the flash device in response to a voltage pulse of predetermined magnitude in order to cause the flash device to produce a flash, means operative when the vacuum tube has been rendered conducting to a predetermined degree to supply to the output circuit from a source of energy a voltage suflicient to impress a voltage pulse of the predetermined magnitude upon the energizing means, means for periodically initially changing the bias of the control electrode slightly in order periodically to render the vacuum tube slightly conducting, thereby periodically to initiate the supply of a slight amount of energy from the source to the output circuit, and means operative through the cooperation of the primary and secondary windings to cause the input circuit, upon the vacuum tube becoming slightly conducting, cumulatively to increase the change in the bias of the control electrode periodically in order cumulatively to draw energy from the output circuit to render the vacuum tube cumulatively increasingly conducting periodically in order cumulatively to increase the conduction of the vacuum tube to the predetermined degree periodically, thereby periodically to impress voltage pulses of the predetermined magnitude upon the energizing means in order to cause the flash device to produce flashes periodically.

26. A stroboscope having, in combination, a. flash device, a transformer having a primary winding and a secondary winding, a vacuum tube having two main electrodes, a control electrode, an input circuit connected to one of the main electrodes and the control electrode in which the secondary winding is connected and an output circuit connected to the main electrodes in which the primary winding is connected, means for normally biasing the control electrode negatively to maintain the vacuum tube normally non-conducting when not in operation, means coupled to the output circuit for energizing the flash device in response to a voltage pulse of predetermined magnitude in order to cause the flash device to produce a hash, means operative when the vacuum tube has been rendered conducting to a predetermined degree to supply to the output circuit from a source of energy a voltage sufficient to impress a voltage pulse of the predetermined magnitude upon the energizing means, means for periodically initially impressing a slightly positive voltage on the control electrode to render the vacuum tube slightly conducting, thereby periodically to initiate the supply of a slight amount of energy from the source to the output circuit, and means operative through the cooperation of the primary and secondary windings to cause the input circuit, upon the vacuum tube becoming slightly conducting, cumulatively to increase the positive voltage on the control electrode periodically in order cumulatively to draw energy from the output circuit to render the vacuum tube cumulatively increasingly conducting periodically in order cumulatively to increase the conduction of the vacuum tube to the predetermined degree periodically, thereby periodically to impress voltage pulses of the predetermined magnitude upon the energizing means in order to cause the flash device to produce flashes periodically.

2'7. A stroboscope having, in combination, a flash device, a condenser, means for charging the condenser, a transformer having a primary Winding and a secondary winding, a vacuum tube having two electrodes, a control electrode, an input circuit connected to one of the main elec trodes and the control electrode in which the secondary winding is connected and an output circuit connected to the main electrodes in which the primary winding is connected, means for biasing the control electrode negatively to maintain the vacuum tube normally non-conducting when not in operation, means coupled to the output circuit for energizing the flash device in response to a voltage pulse of predetermined magnitude in order to discharge the condenser through the flash device to cause the flash device to produce a flash, means operative when the vacuum tube has been rendered conducting to a predetermined degree to supply to the output circuit from a source of energy a voltage sufficient to impress a voltage pulse of the predetermined magnitude upon the energizing means, means for periodically impressing a slightly positive voltage pulse on the control electrode to render the vacuum tube slightly conducting, thereby periodically to initiate the supply of a slight amount of energy from the source to the output circuit, and means operative through the cooperation of the primary and secondary windings to cause the input circuit, upon the vacuum tube becoming slightly conducting, cumulatively to increase the positive voltage on the control electrode periodically in order cumulatively to draw energy from the output circuit to render the vacuum tube cumulatively increasingly conducting periodically in order cumulatively to increase the conduction of the vacuum tube to the predetermined degree periodically, thereby periodically to impress voltage pulses of the predetermined magnitude upon the energizing means in order to discharge the condenser through the flash device periodically to cause the flash device to produce flashes periodically.

28. A stroboscope having, in combination, a hash device, a first condenser, means for charging the first condenser, a transformer having a primary winding and a secondary winding, a second condenser, a vacuum tube having two main electrodes, a control electrode, an input circuit connected to one of the main electrodes and the control electrode in which the secondary winding and the second condenser are connected and an output circuit connected to the main electrodes in which the primary winding is connected, means for normally biasing the control electrode negatively to maintain the vacuum tube normally non-conducting when not in operation, means coupled to the output circuit for energizing the flash device in response to a voltage pulse of predetermined magnitude in order to discharge the first condenser through the hash device to cause the flash device to produce a flash, means operative when the vacuum tube has been rendered conductive to a predetermined degree to supply to the output circuit from a source of energy a voltage sufficient to impress a voltage pulse of the predetermined magnitude upon the energizing means, means for periodically initially impressing a slightly positive voltage pulse on the control electrode to render the vacuum tube slightly conducting, thereby periodically to initiate the supply of a slight amount of energy from the source to the output circuit, and means operative through the cooperation of the primary and secondary windings to cause the input circuit, upon the vacuum tube becoming slightly conducting, cumulatively to increase the positive voltage on the control electrode periodically in order cumulatively to draw energy from the output circuit to render the vacuum tube cumulatively increasingly conducting periodically in order cumulatively to increase the conduction of the vacuum tube to the predetermined degree periodically and cumulatively to charge the second condenser periodically during the periodic cumulative increase of the positive voltage on the control electrode in order to restore the normal negative bias of the control electrode periodically, thereby periodically to impress voltage pulses of the predetermined magnitude upon the energizing means in order to discharge the first condenser through the flash device periodically to cause the flash device to produce flashes periodically.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,043,484 Miller June 9, 1936 2,186,013 Edgerton Jan. 9, 1940 2,310,092 Knowles Feb. 2, 1943 2,426,602 Edgerton Sept. 2, 1947 

